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Viruses, Volume 12, Issue 6 (June 2020) – 110 articles

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Cover Story (view full-size image) Human cytomegalovirus (HCMV) encodes the G protein-coupled receptor (GPCR) homologs US28 and UL33. [...] Read more.
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Open AccessArticle
The Outcome of Porcine Foetal Infection with Bungowannah Virus Is Dependent on the Stage of Gestation at Which Infection Occurs. Part 1: Serology and Virology
Viruses 2020, 12(6), 691; https://doi.org/10.3390/v12060691 - 26 Jun 2020
Cited by 1 | Viewed by 276
Abstract
Bungowannah virus is a novel porcine pestivirus identified in a disease outbreak in Australia in 2003. The aim of this study was to determine the outcome of infection of the pregnant pig with this virus. Twenty-four pregnant pigs were infected at days 35, [...] Read more.
Bungowannah virus is a novel porcine pestivirus identified in a disease outbreak in Australia in 2003. The aim of this study was to determine the outcome of infection of the pregnant pig with this virus. Twenty-four pregnant pigs were infected at days 35, 55, 75 or 90 of gestation. Blood, tonsillar and rectal swabs were collected from each pig at birth and then weekly until euthanasia or death. Tissues were sampled at necropsy. Viral load was measured by real-time reverse-transcription polymerase chain reaction (qRT-PCR) and antibody levels in serum by peroxidase-linked immunoassay. Bungowannah virus was detected in the serum and excretions of all infected pigs at birth regardless of the stage of gestation at which infection occurred. Persistent infections occurred following infection prior to the development of foetal immunocompetence. Unexpectedly some animals infected at day 55 of gestation later cleared the virus and seroconverted. Viraemia and viral shedding resolved quickest following infection in late gestation. Full article
(This article belongs to the Special Issue Bovine Viral Diarrhea Virus and Related Pestiviruses)
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Open AccessArticle
Infection of Ruminants, Including Pregnant Cattle, with Bungowannah Virus
Viruses 2020, 12(6), 690; https://doi.org/10.3390/v12060690 - 26 Jun 2020
Viewed by 300
Abstract
Bungowannah virus is a pestivirus known to cause reproductive losses in pigs. The virus has not been found in other species, nor is it known if it has the capacity to cause disease in other animals. Eight sheep, eight calves and seven pregnant [...] Read more.
Bungowannah virus is a pestivirus known to cause reproductive losses in pigs. The virus has not been found in other species, nor is it known if it has the capacity to cause disease in other animals. Eight sheep, eight calves and seven pregnant cows were experimentally infected with Bungowannah virus. It was found that sheep and calves could be infected. Furthermore, it was shown that the virus is able to cross the bovine placenta and cause infection of the foetus. These findings demonstrate the potential for species other than pigs to become infected with Bungowannah virus and the need to prevent them from becoming infected. Full article
(This article belongs to the Special Issue Bovine Viral Diarrhea Virus and Related Pestiviruses)
Open AccessArticle
HHV-6 Infection and Chemokine RANTES Signaling Pathway Disturbance in Patients with Autoimmune Thyroiditis
Viruses 2020, 12(6), 689; https://doi.org/10.3390/v12060689 - 26 Jun 2020
Viewed by 259
Abstract
The aim of this study was to investigate the role of human herpesvirus-6 (HHV-6) in autoimmune thyroiditis (AIT) development. We examined the possible involvement of HHV-6 gene expression encoding immunomodulating proteins U12 and U51 in AIT development and their role in the modulation [...] Read more.
The aim of this study was to investigate the role of human herpesvirus-6 (HHV-6) in autoimmune thyroiditis (AIT) development. We examined the possible involvement of HHV-6 gene expression encoding immunomodulating proteins U12 and U51 in AIT development and their role in the modulation of chemokine signaling. One hundred patients with autoimmune thyroiditis following thyroidectomy were enrolled in this study. Nested polymerase chain reaction (nPCR) was used to detect the HHV-6 sequence in DNA samples. Reverse transcription PCR (RT-PCR) with three different HHV-6 gene targets (U79/80, U51 and U12) was to detect active infection markers. HHV-6 load was identified using a commercial real-time PCR kit. Immunohistochemistry was performed to investigate the expression of the HHV-6 antigen and RANTES (Regulated upon Activation, Normal T Cell Expressed and Secreted) in thyroid gland tissue. Different commercial immunosorbent assay kits were used for the detection of RANTES, IFNγ, IL-6, and TNFα levels in the AIT patient group and controls. We detected 98% presence of the HHV-6 genomic sequence in AIT patients’ thyroid gland tissues. Markers of active HHV-6 infection (HHV-6 U79/80, U12 and/or U51 mRNA) were predominant in AIT patients’ thyroid tissue samples in comparison with the control group (56% vs. 6%). Evidence from immunofluorescence microscopy showed that HHV-6 can persist in thyrocytes and can interact with RANTES. Visual confirmation of the intense immunofluorescence signal of RANTES detected in thyroid tissues could indicate high expression of this chemokine in the thyroid gland. On the other hand, immunosorbent assays showed very low RANTES levels in AIT patients’ peripheral plasma. These results indicate that RANTES level in AIT patients could be influenced by HHV-6 activation, which in turn may aid AIT development. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessCommunication
Localization of Tobacco Yellow Dwarf Virus Replication Using the In Plant Activation (INPACT) Expression Platform
Viruses 2020, 12(6), 688; https://doi.org/10.3390/v12060688 - 26 Jun 2020
Viewed by 296
Abstract
Geminiviruses and their diseases are a considerable economic threat to a vast number of crops worldwide. Investigating how and where these viruses replicate and accumulate in their hosts may lead to novel molecular resistance strategies. In this study, we used the Rep-inducible In [...] Read more.
Geminiviruses and their diseases are a considerable economic threat to a vast number of crops worldwide. Investigating how and where these viruses replicate and accumulate in their hosts may lead to novel molecular resistance strategies. In this study, we used the Rep-inducible In Plant Activation (INPACT) expression platform, based on the genome of tobacco yellow dwarf virus (TYDV), to determine where this model mastrevirus replicates in its host tobacco. By developing an infectious clone of TYDV and optimizing its delivery by agroinfiltration, we first established an efficient artificial infection process. When delivered into transgenic tobacco plants containing a TYDV-based INPACT cassette encoding the β-glucuronidase (GUS) reporter, we showed the virus activates GUS expression. Histology revealed that reporter gene expression was limited to phloem-associated cell types suggesting TYDV replication has a restricted tissue tropism. Full article
(This article belongs to the Section Viruses of Plants, Fungi and Protozoa)
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Open AccessArticle
Live Visualization of Hemagglutinin Dynamics during Infection by Using a Novel Reporter Influenza A Virus
Viruses 2020, 12(6), 687; https://doi.org/10.3390/v12060687 - 26 Jun 2020
Viewed by 685
Abstract
Live visualization of influenza A virus (IAV) structural proteins during viral infection in cells is highly sought objective to study different aspects of the viral replication cycle. To achieve this, we engineered an IAV to express a Tetra Cysteine tag (TC tag) from [...] Read more.
Live visualization of influenza A virus (IAV) structural proteins during viral infection in cells is highly sought objective to study different aspects of the viral replication cycle. To achieve this, we engineered an IAV to express a Tetra Cysteine tag (TC tag) from hemagglutinin (HA), which allows intracellular labeling of the engineered HA protein with biarsenic dyes and subsequent fluorescence detection. Using such constructs, we rescued a recombinant IAV with TC tag inserted in HA, in A/Puerto Rico/8/1934(H1N1) background (HA-TC). This recombinant HA-TC tag reporter IAV was replication-competent; however, as compared to wild type PR8 IAV, it was attenuated in multicycle replication. We confirmed expression of TC tag and biarsenical labeling of HA by immunofluorescence assay in cells infected with an HA-TC tag reporter IAV. Further, we used this reporter virus to visualize HA expression and translocation in IAV infected cells by live confocal imaging. We also tested the utility of the HA-TC IAV in testing chemical inhibitors of the HA translocation. Overall, HA-TC IAV is a versatile tool that will be useful for studying viral life cycle events, virus-host interactions, and anti-viral testing. Full article
(This article belongs to the Special Issue Influenza A Virus: Host-Virus Relationship)
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Open AccessArticle
Development and Evaluation of a duo SARS-CoV-2 RT-qPCR Assay Combining Two Assays Approved by the World Health Organization Targeting the Envelope and the RNA-Dependant RNA Polymerase (RdRp) Coding Regions
Viruses 2020, 12(6), 686; https://doi.org/10.3390/v12060686 - 25 Jun 2020
Viewed by 421
Abstract
The recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) worldwide has highlighted the importance of reliable and rapid diagnostic testing to prevent and control virus circulation. Dozens of monoplex in-house RT-qPCR assays are already available; however, the development of dual-target assays [...] Read more.
The recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) worldwide has highlighted the importance of reliable and rapid diagnostic testing to prevent and control virus circulation. Dozens of monoplex in-house RT-qPCR assays are already available; however, the development of dual-target assays is suited to avoid false-negative results caused by polymorphisms or point mutations, that can compromise the accuracy of diagnostic and screening tests. In this study, two mono-target assays recommended by WHO (E-Sarbeco (enveloppe gene, Charite University, Berlin, Germany) and RdRp-IP4 (RdRp, Institut Pasteur, Paris, France)) were selected and combined in a unique robust test; the resulting duo SARS-CoV-2 RT-qPCR assay was compared to the two parental monoplex tests. The duo SARS-CoV-2 assay performed equally, or better, in terms of sensitivity, specificity, linearity and signal intensity. We demonstrated that combining two single systems into a dual-target assay (with or without an MS2-based internal control) did not impair performances, providing a potent tool adapted for routine molecular diagnosis in clinical microbiology laboratories. Full article
(This article belongs to the Special Issue Pathogenesis of Human and Animal Coronaviruses)
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Open AccessArticle
Differential Growth Characteristics of Crimean-Congo Hemorrhagic Fever Virus in Kidney Cells of Human and Bovine Origin
Viruses 2020, 12(6), 685; https://doi.org/10.3390/v12060685 - 25 Jun 2020
Viewed by 353
Abstract
Crimean-Congo hemorrhagic fever virus (CCHFV) causes a lethal tick-borne zoonotic disease with severe clinical manifestation in humans but does not produce symptomatic disease in wild or domestic animals. The factors contributing to differential outcomes of infection between species are not yet understood. Since [...] Read more.
Crimean-Congo hemorrhagic fever virus (CCHFV) causes a lethal tick-borne zoonotic disease with severe clinical manifestation in humans but does not produce symptomatic disease in wild or domestic animals. The factors contributing to differential outcomes of infection between species are not yet understood. Since CCHFV is known to have tropism to kidney tissue and cattle play an important role as an amplifying host for CCHFV, in this study, we assessed in vitro cell susceptibility to CCHFV infection in immortalized and primary kidney and adrenal gland cell lines of human and bovine origin. Based on our indirect fluorescent focus assay (IFFA), we suggest a cell-to-cell CCHF viral spread process in bovine kidney cells but not in human cells. Over the course of seven days post-infection (dpi), infected bovine kidney cells are found in restricted islet-like areas. In contrast, three dpi infected human kidney or adrenal cells were noted in areas distant from one another yet progressed to up to 100% infection of the monolayer. Pronounced CCHFV replication, measured by quantitative real-time RT-PCR (qRT-PCR) of both intra- and extracellular viral RNA, was documented only in human kidney cells, supporting restrictive infection in cells of bovine origin. To further investigate the differences, lactate dehydrogenase activity and cytopathic effects were measured at different time points in all mentioned cells. In vitro assays indicated that CCHFV infection affects human and bovine kidney cells differently, where human cell lines seem to be markedly permissive. This is the initial reporting of CCHFV susceptibility and replication patterns in bovine cells and the first report to compare human and animal cell permissiveness in vitro. Further investigations will help to understand the impact of different cell types of various origins on the virus–host interaction. Full article
(This article belongs to the Special Issue Emerging Arboviruses)
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Open AccessArticle
BLI-Based Functional Assay in Phage Display Benefits the Development of a PD-L1-Targeting Therapeutic Antibody
Viruses 2020, 12(6), 684; https://doi.org/10.3390/v12060684 - 25 Jun 2020
Viewed by 268
Abstract
The therapeutic functionality of the antibodies from phage display is verified after an initial screening. Several immunological assays such as ELISA, flow cytometry, the western blot, and surface plasmon resonance (SPR) assay are commonly used; the IgG-format antibody is usually preferred to verify [...] Read more.
The therapeutic functionality of the antibodies from phage display is verified after an initial screening. Several immunological assays such as ELISA, flow cytometry, the western blot, and surface plasmon resonance (SPR) assay are commonly used; the IgG-format antibody is usually preferred to verify the functionality of antibodies, which need elaborative mammalian expression and purification work. Here, we describe a biolayer interferometry (BLI)-based assay that can evaluate the inhibitory functions of antibodies at an earlier stage of screening. To develop a PD-L1-targeting antibody from phage display, we applied the BLI assay to the initial scFv antibody screening, in addition to common ELISA and fluorescence-activated cell sorting (FACS) assays, which showed high advantages and relevance with the in vitro cell-based PD-1/PD-L1 inhibition assay. The same assays for IgG-format antibodies showed high efficiency of the BLI assay in the functional characterization of antibodies, and one candidate selected from the BLI assay resulted in highly efficacious antitumor activity in an in vivo syngeneic mouse study. The BLI assay was also beneficial when searching for antibodies with diverse epitopes. These results demonstrated that the BLI-based inhibition assay is an excellent technique for high-throughput scFv antibody screening in earlier stages and can make phage-display antibody screening more efficient to develop therapeutic candidates. Full article
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Open AccessReview
Nuclear Egress Complexes of HCMV and Other Herpesviruses: Solving the Puzzle of Sequence Coevolution, Conserved Structures and Subfamily-Spanning Binding Properties
Viruses 2020, 12(6), 683; https://doi.org/10.3390/v12060683 - 24 Jun 2020
Viewed by 387
Abstract
Herpesviruses uniquely express two essential nuclear egress-regulating proteins forming a heterodimeric nuclear egress complex (core NEC). These core NECs serve as hexameric lattice-structured platforms for capsid docking and recruit viral and cellular NEC-associated factors that jointly exert nuclear lamina as well as membrane-rearranging [...] Read more.
Herpesviruses uniquely express two essential nuclear egress-regulating proteins forming a heterodimeric nuclear egress complex (core NEC). These core NECs serve as hexameric lattice-structured platforms for capsid docking and recruit viral and cellular NEC-associated factors that jointly exert nuclear lamina as well as membrane-rearranging functions (multicomponent NEC). The regulation of nuclear egress has been profoundly analyzed for murine and human cytomegaloviruses (CMVs) on a mechanistic basis, followed by the description of core NEC crystal structures, first for HCMV, then HSV-1, PRV and EBV. Interestingly, the highly conserved structural domains of these proteins stand in contrast to a very limited sequence conservation of the key amino acids within core NEC-binding interfaces. Even more surprising, although a high functional consistency was found when regarding the basic role of NECs in nuclear egress, a clear specification was identified regarding the limited, subfamily-spanning binding properties of core NEC pairs and NEC multicomponent proteins. This review summarizes the evolving picture of the relationship between sequence coevolution, structural conservation and properties of NEC interaction, comparing HCMV to α-, β- and γ-herpesviruses. Since NECs represent substantially important elements of herpesviral replication that are considered as drug-accessible targets, their putative translational use for antiviral strategies is discussed. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessReview
Role of the Guanine Nucleotide Exchange Factor GBF1 in the Replication of RNA Viruses
Viruses 2020, 12(6), 682; https://doi.org/10.3390/v12060682 - 24 Jun 2020
Viewed by 294
Abstract
The guanine nucleotide exchange factor GBF1 is a well-known factor that can activate different ADP-ribosylation factor (Arf) proteins during the regulation of different cellular vesicular transport processes. In the last decade, it has become increasingly evident that GBF1 can also regulate different steps [...] Read more.
The guanine nucleotide exchange factor GBF1 is a well-known factor that can activate different ADP-ribosylation factor (Arf) proteins during the regulation of different cellular vesicular transport processes. In the last decade, it has become increasingly evident that GBF1 can also regulate different steps of the replication cycle of RNA viruses belonging to different virus families. GBF1 has been shown not only to facilitate the intracellular traffic of different viral and cellular elements during infection, but also to modulate the replication of viral RNA, the formation and maturation of viral replication complexes, and the processing of viral proteins through mechanisms that do not depend on its canonical role in intracellular transport. Here, we review the various roles that GBF1 plays during the replication of different RNA viruses. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle
PCR Detection and Phylogenetic Analysis of Megalocytivirus Isolates in Farmed Giant Sea Perch Lates calcarifer in Southern Taiwan
Viruses 2020, 12(6), 681; https://doi.org/10.3390/v12060681 - 24 Jun 2020
Viewed by 284
Abstract
The Megalocytivirus genus includes three genotypes, red sea bream iridovirus (RSIV), infectious spleen and kidney necrosis virus (ISKNV), and turbot reddish body iridovirus (TRBIV), and has caused mass mortalities in various marine and freshwater fish species in East and Southeast Asia. Of the [...] Read more.
The Megalocytivirus genus includes three genotypes, red sea bream iridovirus (RSIV), infectious spleen and kidney necrosis virus (ISKNV), and turbot reddish body iridovirus (TRBIV), and has caused mass mortalities in various marine and freshwater fish species in East and Southeast Asia. Of the three genotypes, TRBIV-like megalocytivirus is not included in the World Organization for Animal Health (OIE)-reportable virus list because of its geographic restriction and narrow host range. In 2017, 39 cases of suspected iridovirus infection were isolated from fingerlings of giant sea perch (Lates calcarifer) cultured in southern Taiwan during megalocytivirus epizootics. Polymerase chain reaction (PCR) with different specific primer sets was undertaken to identify the causative agent. Our results revealed that 35 out of the 39 giant sea perch iridovirus (GSPIV) isolates were TRBIV-like megalocytiviruses. To further evaluate the genetic variation, the nucleotide sequences of major capsid protein (MCP) gene (1348 bp) from 12 of the 35 TRBIV-like megalocytivirus isolates were compared to those of other known. High nucleotide sequence identity showed that these 12 TRBIV-like GSPIV isolates are the same species. Phylogenetic analysis based on the MCP gene demonstrated that these 12 isolates belong to the clade II of TRBIV megalocytiviruses, and are distinct from RSIV and ISKNV. In conclusion, the GSPIV isolates belonging to TRBIV clade II megalocytiviruses have been introduced into Taiwan and caused a severe impact on the giant sea perch aquaculture industry. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle
Prevalence and Genetic Diversity of Atypical Porcine Pestivirus (APPV) Detected in South Korean Wild Boars
Viruses 2020, 12(6), 680; https://doi.org/10.3390/v12060680 - 24 Jun 2020
Viewed by 280
Abstract
Atypical porcine pestivirus (APPV), currently classified as pestivirus K, causes congenital tremor (CT) type A-II in piglets. Eighteen APPV strains were identified from 2297 South Korean wild boars captured in 2019. Phylogenetic analysis of the structural protein E2 and nonstructural proteins NS3 [...] Read more.
Atypical porcine pestivirus (APPV), currently classified as pestivirus K, causes congenital tremor (CT) type A-II in piglets. Eighteen APPV strains were identified from 2297 South Korean wild boars captured in 2019. Phylogenetic analysis of the structural protein E2 and nonstructural proteins NS3 and Npro classified the APPV viruses, including reference strains, into Clades I, II and III. Clade I was divided into four subclades; however, the strains belonging to the four subclades differed slightly, depending on the tree analysis, the NS3, E2, and Npro genes. The maximum-likelihood method was assigned to South Korean wild boar APPV strains to various subclades within the three trees: subclades I.1 and I.2 in the E2 tree, subclade I.1 in the Npro tree, and subclades I.1 and I.4 in the NS3 ML tree. In conclusion, APPV among South Korean wild boars belonging to Clade I may be circulating at a higher level than among the South Korean domestic pig populations. Full article
(This article belongs to the Special Issue Bovine Viral Diarrhea Virus and Related Pestiviruses)
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Open AccessArticle
Host–Pathogen Responses to Pandemic Influenza H1N1pdm09 in a Human Respiratory Airway Model
Viruses 2020, 12(6), 679; https://doi.org/10.3390/v12060679 - 24 Jun 2020
Viewed by 857
Abstract
The respiratory Influenza A Viruses (IAVs) and emerging zoonotic viruses such as Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) pose a significant threat to human health. To accelerate our understanding of the host–pathogen response to respiratory viruses, the use of more complex in vitro systems [...] Read more.
The respiratory Influenza A Viruses (IAVs) and emerging zoonotic viruses such as Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) pose a significant threat to human health. To accelerate our understanding of the host–pathogen response to respiratory viruses, the use of more complex in vitro systems such as normal human bronchial epithelial (NHBE) cell culture models has gained prominence as an alternative to animal models. NHBE cells were differentiated under air-liquid interface (ALI) conditions to form an in vitro pseudostratified epithelium. The responses of well-differentiated (wd) NHBE cells were examined following infection with the 2009 pandemic Influenza A/H1N1pdm09 strain or following challenge with the dsRNA mimic, poly(I:C). At 30 h postinfection with H1N1pdm09, the integrity of the airway epithelium was severely impaired and apical junction complex damage was exhibited by the disassembly of zona occludens-1 (ZO-1) from the cell cytoskeleton. wdNHBE cells produced an innate immune response to IAV-infection with increased transcription of pro- and anti-inflammatory cytokines and chemokines and the antiviral viperin but reduced expression of the mucin-encoding MUC5B, which may impair mucociliary clearance. Poly(I:C) produced similar responses to IAV, with the exception of MUC5B expression which was more than 3-fold higher than for control cells. This study demonstrates that wdNHBE cells are an appropriate ex-vivo model system to investigate the pathogenesis of respiratory viruses. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle
Genetic Diversity of Potassium Ion Channel Proteins Encoded by Chloroviruses That Infect Chlorella heliozoae
Viruses 2020, 12(6), 678; https://doi.org/10.3390/v12060678 - 23 Jun 2020
Viewed by 441
Abstract
Chloroviruses are large, plaque-forming, dsDNA viruses that infect chlorella-like green algae that live in a symbiotic relationship with protists. Chloroviruses have genomes from 290 to 370 kb, and they encode as many as 400 proteins. One interesting feature of chloroviruses is that they [...] Read more.
Chloroviruses are large, plaque-forming, dsDNA viruses that infect chlorella-like green algae that live in a symbiotic relationship with protists. Chloroviruses have genomes from 290 to 370 kb, and they encode as many as 400 proteins. One interesting feature of chloroviruses is that they encode a potassium ion (K+) channel protein named Kcv. The Kcv protein encoded by SAG chlorovirus ATCV-1 is one of the smallest known functional K+ channel proteins consisting of 82 amino acids. The KcvATCV-1 protein has similarities to the family of two transmembrane domain K+ channel proteins; it consists of two transmembrane α-helixes with a pore region in the middle, making it an ideal model for studying K+ channels. To assess their genetic diversity, kcv genes were sequenced from 103 geographically distinct SAG chlorovirus isolates. Of the 103 kcv genes, there were 42 unique DNA sequences that translated into 26 new Kcv channels. The new predicted Kcv proteins differed from KcvATCV-1 by 1 to 55 amino acids. The most conserved region of the Kcv protein was the filter, the turret and the pore helix were fairly well conserved, and the outer and the inner transmembrane domains of the protein were the most variable. Two of the new predicted channels were shown to be functional K+ channels. Full article
(This article belongs to the Section Viruses of Plants, Fungi and Protozoa)
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Open AccessArticle
Abrogation of Constitutive and Induced Type I and Type III Interferons and Interferon-Stimulated Genes in Keratinocytes by Canine Papillomavirus 2 E6 and E7
Viruses 2020, 12(6), 677; https://doi.org/10.3390/v12060677 - 23 Jun 2020
Viewed by 344
Abstract
Cutaneous papillomaviruses can cause severe, persistent infections and skin cancer in immunodeficient patients, including people with X-linked severe combined immunodeficiency (XSCID). A similar phenotype is observed in a canine model of XSCID; these dogs acquire severe cutaneous papillomavirus infections that can progress to [...] Read more.
Cutaneous papillomaviruses can cause severe, persistent infections and skin cancer in immunodeficient patients, including people with X-linked severe combined immunodeficiency (XSCID). A similar phenotype is observed in a canine model of XSCID; these dogs acquire severe cutaneous papillomavirus infections that can progress to cancer in association with canine papillomavirus type 2 (CPV2). This canine model system provides a natural spontaneous animal model for investigation of papillomavirus infections in immunodeficient patients. Currently, it is unknown if CPV2 can subvert the innate immune system and interfere with its ability to express antiviral cytokines, which are critical in the host defense against viral pathogens. The aim of the current study was to determine if the oncogenes E6 and E7 from CPV2 interfere with expression of antiviral cytokines in keratinocytes, the target cells of papillomavirus infections. We determined that E6 but not E7 interferes with the constitutive expression of some antiviral cytokines, including interferon (IFN)-β and the IFN-stimulated gene IFIT1. Both E6 and E7 interfere with the transcriptional upregulation of the antiviral cytokines in response to stimulation with the dsDNA Poly(dA:dT). In contrast, while E6 also interferes with the transcriptional upregulation of antiviral cytokines in response to stimulation with the dsRNA Poly(I:C), E7 interferes with only a subset of these antiviral cytokines. Finally, we demonstrated that E7 but not E6 abrogates signaling through the type I IFN receptor. Taken together, CPV2 E6 and E7 both impact expression of antiviral cytokines in canine keratinocytes, albeit likely through different mechanisms. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle
The C962R ORF of African Swine Fever Strain Georgia Is Non-Essential and Not Required for Virulence in Swine
Viruses 2020, 12(6), 676; https://doi.org/10.3390/v12060676 - 23 Jun 2020
Viewed by 363
Abstract
African swine fever virus (ASFV) is the causative agent of the African swine fever (ASF) epizootic currently affecting pigs throughout Eurasia, causing significant economic losses in the swine industry. The virus genome encodes for more than 160 genes, of which only a few [...] Read more.
African swine fever virus (ASFV) is the causative agent of the African swine fever (ASF) epizootic currently affecting pigs throughout Eurasia, causing significant economic losses in the swine industry. The virus genome encodes for more than 160 genes, of which only a few have been studied in detail. Here we describe the previously uncharacterized ASFV open reading frame (ORF) C962R, a gene encoding for a putative NTPase. RNA transcription studies using infected swine macrophages demonstrate that the C962R gene is translated as a late virus protein. A recombinant ASFV lacking the C962R gene (ASFV-G-ΔC962R) demonstrates in vivo that the C962R gene is non-essential, since ASFV-G-ΔC962R has similar replication kinetics in primary swine macrophage cell cultures when compared to parental highly virulent field isolate Georgia2007 (ASFV-G). Experimental infection of domestic pigs with ASFV-G-ΔC962R produced a clinical disease similar to that caused by the parental ASFV-G, confirming that deletion of the C962R gene from the ASFV genome does not impact virulence. Full article
(This article belongs to the Special Issue Endemic and Emerging Swine Viruses)
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Open AccessArticle
Arbuscular Mycorrhizal Symbiosis Primes Tolerance to Cucumber Mosaic Virus in Tomato
Viruses 2020, 12(6), 675; https://doi.org/10.3390/v12060675 - 22 Jun 2020
Viewed by 336
Abstract
Tomato plants can establish symbiotic interactions with arbuscular mycorrhizal fungi (AMF) able to promote plant nutrition and prime systemic plant defenses against pathogens attack; the mechanism involved is known as mycorrhiza-induced resistance (MIR). However, studies on the effect of AMF on viral infection, [...] Read more.
Tomato plants can establish symbiotic interactions with arbuscular mycorrhizal fungi (AMF) able to promote plant nutrition and prime systemic plant defenses against pathogens attack; the mechanism involved is known as mycorrhiza-induced resistance (MIR). However, studies on the effect of AMF on viral infection, still limited and not conclusive, indicate that AMF colonization may have a detrimental effect on plant defenses against viruses, so that the term “mycorrhiza-induced susceptibility” (MIS) has been proposed for these cases. To expand the case studies to a not yet tested viral family, that is, Bromoviridae, we investigated the effect of the colonization by the AMF Funneliformis mosseae on cucumber mosaic virus (CMV) infection in tomato by phenotypic, physiological, biochemical, and transcriptional analyses. Our results showed that the establishment of a functional AM symbiosis is able to limit symptoms development. Physiological and transcriptomic data highlighted that AMF mitigates the drastic downregulation of photosynthesis-related genes and the reduction of photosynthetic CO2 assimilation rate caused by CMV infection. In parallel, an increase of salicylic acid level and a modulation of reactive oxygen species (ROS)-related genes, toward a limitation of ROS accumulation, was specifically observed in CMV-infected mycorrhizal plants. Overall, our data indicate that the AM symbiosis influences the development of CMV infection in tomato plants and exerts a priming effect able to enhance tolerance to viral infection. Full article
(This article belongs to the Section Viruses of Plants, Fungi and Protozoa)
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Open AccessArticle
Prolonged Detection of Bovine Viral Diarrhoea Virus Infection in the Semen of Bulls
Viruses 2020, 12(6), 674; https://doi.org/10.3390/v12060674 - 22 Jun 2020
Viewed by 375
Abstract
Infection of bulls with bovine viral diarrhoea virus (BVDV) can result in the development of virus persistence, confined to the reproductive tract. These bulls develop a normal immune response with high neutralizing antibody titres. However, BVDV can be excreted in the semen for [...] Read more.
Infection of bulls with bovine viral diarrhoea virus (BVDV) can result in the development of virus persistence, confined to the reproductive tract. These bulls develop a normal immune response with high neutralizing antibody titres. However, BVDV can be excreted in the semen for a prolonged period. Although relatively rare, in this study we describe six separate cases in bulls being prepared for admission to artificial breeding centres. Semen samples were tested in a pan-Pestivirus-reactive real-time PCR assay and viral RNA was detected in semen from five of the bulls for three to eight months after infection. In one bull, virus was detected at low levels for more than five years. This bull was found to have one small testis. When slaughtered, virus was only detected in the abnormal testis. The low levels of BVDV in the semen of these bulls were only intermittently detected by virus isolation in cell culture. This virus-contaminated semen presents a biosecurity risk and confirms the need to screen all batches of semen from bulls that have been previously infected with BVDV. The use of real-time PCR is recommended as the preferred laboratory assay for this purpose. Full article
(This article belongs to the Special Issue Bovine Viral Diarrhea Virus and Related Pestiviruses)
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Open AccessReview
The Evolution, Spread and Global Threat of H6Nx Avian Influenza Viruses
Viruses 2020, 12(6), 673; https://doi.org/10.3390/v12060673 - 22 Jun 2020
Viewed by 528
Abstract
Avian influenza viruses of the subtype H6Nx are being detected globally with increasing frequency. Some H6Nx lineages are becoming enzootic in Asian poultry and sporadic incursions into European poultry are occurring more frequently. H6Nx viruses that contain mammalian adaptation motifs pose a zoonotic [...] Read more.
Avian influenza viruses of the subtype H6Nx are being detected globally with increasing frequency. Some H6Nx lineages are becoming enzootic in Asian poultry and sporadic incursions into European poultry are occurring more frequently. H6Nx viruses that contain mammalian adaptation motifs pose a zoonotic threat and have caused human cases. Although currently understudied globally, H6Nx avian influenza viruses pose a substantial threat to both poultry and human health. In this review we examine the current state of knowledge of H6Nx viruses including their global distribution, tropism, transmission routes and human health risk. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle
FKBP5 Regulates RIG-I-Mediated NF-κB Activation and Influenza A Virus Infection
Viruses 2020, 12(6), 672; https://doi.org/10.3390/v12060672 - 22 Jun 2020
Viewed by 394
Abstract
Influenza A virus (IAV) is a highly transmissible respiratory pathogen and is a constant threat to global health with considerable economic and social impact. Influenza viral RNA is sensed by host pattern recognition receptors (PRRs), such as the Toll-like receptor 7 (TLR7) and [...] Read more.
Influenza A virus (IAV) is a highly transmissible respiratory pathogen and is a constant threat to global health with considerable economic and social impact. Influenza viral RNA is sensed by host pattern recognition receptors (PRRs), such as the Toll-like receptor 7 (TLR7) and retinoic acid-inducible gene I (RIG-I). The activation of these PRRs instigates the interferon regulatory factor (IRF) and nuclear factor kappa B (NF-κB) signaling pathways that induce the expression of interferon-stimulated genes (ISGs) and inflammatory genes. FK506-binding protein 5 (FKBP5) has been implied in the IκBα kinase (IKK) complex. However, the role of FKBP5 in the RIG-I signaling and IAV infection is not well elucidated. Here, we demonstrate that the knockout of FKBP5 increases IAV infection. Furthermore, FKBP5 binds IKKα, which is critical for RIG-I-induced innate immune responses and ISG expression. Taken together, FKBP5 is a novel anti-influenza host factor that restricts IAV infection by the activation of RIG-I-mediated NF-κB signaling. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle
Flavivirus Infection Associated with Cerebrovascular Events
Viruses 2020, 12(6), 671; https://doi.org/10.3390/v12060671 - 22 Jun 2020
Viewed by 562
Abstract
Arthropod-borne viruses (arboviruses) of the genus Flavivirus are distributed globally and cause significant human disease and mortality annually. Flavivirus infections present a spectrum of clinical manifestations, ranging from asymptomatic to severe manifestations, including hemorrhage, encephalitis and death. Herein, we describe 3 case reports [...] Read more.
Arthropod-borne viruses (arboviruses) of the genus Flavivirus are distributed globally and cause significant human disease and mortality annually. Flavivirus infections present a spectrum of clinical manifestations, ranging from asymptomatic to severe manifestations, including hemorrhage, encephalitis and death. Herein, we describe 3 case reports of cerebrovascular involvement in patients infected by dengue and Zika viruses in Sao Jose do Rio Preto, São Paulo State, Brazil, a hyperendemic area for arbovirus circulation, including dengue, yellow fever, chikungunya and Saint Louis encephalitis viruses. Our findings highlight the potential threat that unusual clinical manifestations may pose to arbovirus disease management and recovery. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle
Mutagenic Analysis of a DNA Translocating Tube’s Interior Surface
Viruses 2020, 12(6), 670; https://doi.org/10.3390/v12060670 - 22 Jun 2020
Viewed by 331
Abstract
Bacteriophage ϕX174 uses a decamer of DNA piloting proteins to penetrate its host. These proteins oligomerize into a cell wall-spanning tube, wide enough for genome passage. While the inner surface of the tube is primarily lined with inward-facing amino acid side chains containing [...] Read more.
Bacteriophage ϕX174 uses a decamer of DNA piloting proteins to penetrate its host. These proteins oligomerize into a cell wall-spanning tube, wide enough for genome passage. While the inner surface of the tube is primarily lined with inward-facing amino acid side chains containing amide and guanidinium groups, there is a 28 Å-long section near the tube’s C-terminus that does not exhibit this motif. The majority of the inward-facing residues in this region are conserved across the three ϕX174-like clades, suggesting that they play an important role during genome delivery. To test this hypothesis, and explore the general function of the tube’s inner surface, non-glutamine residues within this region were mutated to glutamine, while existing glutamine residues were changed to serine. Four of the resulting mutants had temperature-dependent phenotypes. Virion assembly, host attachment, and virion eclipse, defined as the cell’s ability to inactivate the virus, were not affected. Genome delivery, however, was inhibited. The results support a model in which a balance of forces governs genome delivery: potential energy provided by the densely packaged viral genome and/or an osmotic gradient move the genome into the cell, while the tube’s inward facing glutamine residues exert a frictional force, or drag, that controls genome release. Full article
(This article belongs to the Special Issue In Memory of Michael Rossmann)
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Open AccessArticle
mRNA Profile in Milk Extracellular Vesicles from Bovine Leukemia Virus-Infected Cattle
Viruses 2020, 12(6), 669; https://doi.org/10.3390/v12060669 - 20 Jun 2020
Viewed by 494
Abstract
Milk extracellular vesicles (EVs) form an excellent source of mRNAs, microRNAs (miRNAs), proteins, and lipids that represent the physiological and pathological status of the host. Recent studies have reported milk EVs as novel biomarkers for many infectious diseases in both humans and animals. [...] Read more.
Milk extracellular vesicles (EVs) form an excellent source of mRNAs, microRNAs (miRNAs), proteins, and lipids that represent the physiological and pathological status of the host. Recent studies have reported milk EVs as novel biomarkers for many infectious diseases in both humans and animals. For example, miRNAs in milk EVs from cattle were used for early detection of bacterial infection in the mammary gland. Based on these findings, we hypothesized that mRNAs in milk EVs are suitable for gaining a better understanding of the pathogenesis of bovine leukemia virus (BLV) infection and prognosis of the clinical stage in cattle. For that purpose, milk EVs were isolated from BLV-infected and uninfected cattle, and mRNAs were investigated using microarray analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed mainly focusing on the differentially expressed genes (DEGs) in milk EVs from BLV-infected cattle. GO and KEGG analyses suggested the DEGs in milk EVs from BLV-infected cattle had involved in diverse molecular functions, biological processes, and distinct disease-related pathways. The present study suggested that BLV infection causes profound effects on host cellular activity, changing the mRNA expression profile in milk EVs obtained from BLV-infected cattle. Overall, our results suggested that the mRNA profile in milk EVs to be a key factor for monitoring the clinical stage of BLV infection. This is the first report of mRNA profiling of milk EVs obtained from BLV-infected cattle. Full article
(This article belongs to the Special Issue Viruses and Extracellular Vesicles)
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Open AccessArticle
Adeno-Associated Virus (AAV) Capsid Stability and Liposome Remodeling During Endo/Lysosomal pH Trafficking
Viruses 2020, 12(6), 668; https://doi.org/10.3390/v12060668 - 20 Jun 2020
Viewed by 536
Abstract
Adeno-associated viruses (AAVs) are small, non-pathogenic ssDNA viruses being used as therapeutic gene delivery vectors for the treatment of a variety of monogenic diseases. An obstacle to successful gene delivery is inefficient capsid trafficking through the endo/lysosomal pathway. This study aimed to characterize [...] Read more.
Adeno-associated viruses (AAVs) are small, non-pathogenic ssDNA viruses being used as therapeutic gene delivery vectors for the treatment of a variety of monogenic diseases. An obstacle to successful gene delivery is inefficient capsid trafficking through the endo/lysosomal pathway. This study aimed to characterize the AAV capsid stability and dynamics associated with this process for a select number of AAV serotypes, AAV1, AAV2, AAV5, and AAV8, at pHs representative of the early and late endosome, and the lysosome (6.0, 5.5, and 4.0, respectively). All AAV serotypes displayed thermal melt temperatures that varied with pH. The stability of AAV1, AAV2, and AAV8 increased in response to acidic conditions and then decreased at pH 4.0. In contrast, AAV5 demonstrated a consistent decrease in thermostability in response to acidification. Negative-stain EM visualization of liposomes in the presence of capsids at pH 5.5 or when heat shocked showed induced remodeling consistent with the externalization of the PLA2 domain of VP1u. These observations provide clues to the AAV capsid dynamics that facilitate successful infection. Finally, transduction assays revealed a pH and temperature dependence with low acidity and temperatures > 4 °C as detrimental factors. Full article
(This article belongs to the Special Issue In Memory of Michael Rossmann)
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Open AccessReview
Recognition of Reovirus RNAs by the Innate Immune System
Viruses 2020, 12(6), 667; https://doi.org/10.3390/v12060667 - 20 Jun 2020
Viewed by 387
Abstract
Mammalian orthoreovirus (reovirus) is a dsRNA virus, which has long been used as a model system to study host–virus interactions. One of the earliest interactions during virus infection is the detection of the viral genomic material, and the consequent induction of an interferon [...] Read more.
Mammalian orthoreovirus (reovirus) is a dsRNA virus, which has long been used as a model system to study host–virus interactions. One of the earliest interactions during virus infection is the detection of the viral genomic material, and the consequent induction of an interferon (IFN) based antiviral response. Similar to the replication of related dsRNA viruses, the genomic material of reovirus is thought to remain protected by viral structural proteins throughout infection. Thus, how innate immune sensor proteins gain access to the viral genomic material, is incompletely understood. This review summarizes currently known information about the innate immune recognition of the reovirus genomic material. Using this information, we propose hypotheses about host detection of reovirus. Full article
(This article belongs to the Special Issue Reoviruses)
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Open AccessCommentary
Dry Panels Supporting External Quality Assessment Programs for Next Generation Sequencing-Based HIV Drug Resistance Testing
Viruses 2020, 12(6), 666; https://doi.org/10.3390/v12060666 - 20 Jun 2020
Cited by 1 | Viewed by 303
Abstract
External quality assessment (EQA) is a keystone element in the validation and implementation of next generation sequencing (NGS)-based HIV drug resistance testing (DRT). Software validation and evaluation is a critical element in NGS EQA programs. While the development, sharing, and adoption of wet [...] Read more.
External quality assessment (EQA) is a keystone element in the validation and implementation of next generation sequencing (NGS)-based HIV drug resistance testing (DRT). Software validation and evaluation is a critical element in NGS EQA programs. While the development, sharing, and adoption of wet lab protocols is coupled with the increasing access to NGS technology worldwide, rendering it easy to produce NGS data for HIV-DRT, bioinformatic data analysis remains a bottleneck for most of the diagnostic laboratories. Several computational tools have been made available, via free or commercial sources, to automate the conversion of raw NGS data into an actionable clinical report. Although different software platforms yield equivalent results when identical raw NGS datasets are analyzed for variations at higher abundance, discrepancies arise when variations at lower frequencies are considered. This implies that validation and performance assessment of the bioinformatics tools applied in NGS HIV-DRT is critical, and the origins of the observed discrepancies should be determined. Well-characterized reference NGS datasets with ground truth on the genotype composition at all examined loci and the exact frequencies of HIV variations they may harbor, so-called dry panels, would be essential in such cases. The strategic design and construction of such panels are challenging but imperative tasks in support of EQA programs for NGS-based HIV-DRT and the validation of relevant bioinformatics tools. Here, we present criteria that can guide the design of such dry panels, which were discussed in the Second International Winnipeg Symposium themed for EQA strategies for NGS HIVDR assays. Full article
(This article belongs to the Special Issue Next Generation Sequencing for HIV Drug Resistance Testing)
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Open AccessArticle
Extracellular Vesicle Activation of Latent HIV-1 Is Driven by EV-Associated c-Src and Cellular SRC-1 via the PI3K/AKT/mTOR Pathway
Viruses 2020, 12(6), 665; https://doi.org/10.3390/v12060665 - 19 Jun 2020
Viewed by 388
Abstract
HIV-1 is a global health crisis that has infected more than 37 million people. Latent reservoirs throughout the body are a major hurdle when it comes to eradicating the virus. In our previous study, we found that exosomes, a type of extracellular vesicle [...] Read more.
HIV-1 is a global health crisis that has infected more than 37 million people. Latent reservoirs throughout the body are a major hurdle when it comes to eradicating the virus. In our previous study, we found that exosomes, a type of extracellular vesicle (EV), from uninfected cells activate the transcription of HIV-1 in latent infected cells, regardless of combination antiretroviral therapy (cART). In this study, we investigated the specific mechanism behind the EV activation of latent HIV-1. We found that phosphorylated c-Src is present in EVs of various cell lines and has the ability to activate downstream proteins such as EGFR, initiating a signal cascade. EGFR is then able to activate the PI3K/AKT/mTOR pathway, resulting in the activation of STAT3 and SRC-1, culminating in the reversal of HIV-1 latency. This was verified by examining levels of HIV-1 TAR, genomic RNA and HIV-1 Gag p24 protein in cell lines and primary cells. We found that EVs containing c-Src rescued HIV-1 despite the presence of inhibitors, validating the importance of EV-associated c-Src in latent HIV-1 activation. Lastly, we discovered an increased recruitment of p300 and NF-κB in the nucleus of EV-treated infected cells. Collectively, our data suggest that EV-associated c-Src is able to activate latent HIV-1 via the PI3K/AKT/mTOR pathway and SRC-1/p300-driven chromatin remodeling. These findings could aid in designing new strategies to prevent the reactivation of latent HIV-1 in patients under cART. Full article
(This article belongs to the Special Issue Viruses and Extracellular Vesicles)
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Open AccessArticle
Potent and Selective Activity against Human Immunodeficiency Virus 1 (HIV-1) of Thymelaea hirsuta Extracts
Viruses 2020, 12(6), 664; https://doi.org/10.3390/v12060664 - 19 Jun 2020
Viewed by 323
Abstract
Historically, natural products have been the most successful source of inspiration for the development of new drugs. Members of the Thymelaeaceae family have been of interest owing to their excellent medicinal value. Given the successful history of natural product-based drug discovery, extracts from [...] Read more.
Historically, natural products have been the most successful source of inspiration for the development of new drugs. Members of the Thymelaeaceae family have been of interest owing to their excellent medicinal value. Given the successful history of natural product-based drug discovery, extracts from the aerial parts of Thymelaea hirsuta were evaluated for their potential anti-human immunodeficiency virus type 1 (HIV-1) activity. Ethyl acetate extracts from leaves (71B) and branches (72B) of Thymelaea hirsuta showed potent and selective activity against HIV-1 wt (EC50 = 0.8 µg/mL) at non-cytotoxic concentrations (CC50 > 100 µg/mL). They proved to be active against HIV-1 variants carrying clinically relevant NNRTI and NRTI mutations at low concentration (0.3–4 µg/mL range) and against the M-tropic strain HIV-1 BaL. The 72B extract, chosen as a lead, was not able to inhibit the RT and protease enzymatic functions. Furthermore, it was not virucidal, since exposure of HIV to high concentration did not affect virus infectivity. The pre-clinical safety profile of this extract showed no adverse effect on the growth of Lactobacilli, and non-toxic concentration of the extract did not influence the Caco-2 epithelial cells monolayer integrity. Additionally, extract 72B prevented syncytia formation at low concentration (0.4 µg/mL). The potent inhibitory effect on the syncytia formation in co-cultures showed that 72B inhibits an early event in the replication cycle of HIV. All of these findings prompt us to carry on new studies on Thymelaea hirsuta extracts. Full article
(This article belongs to the Section Antivirals & Vaccines)
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Open AccessArticle
Phylogenetic and Geospatial Evidence of Canine Parvovirus Transmission between Wild Dogs and Domestic Dogs at the Urban Fringe in Australia
Viruses 2020, 12(6), 663; https://doi.org/10.3390/v12060663 - 19 Jun 2020
Viewed by 408
Abstract
Canine parvovirus (CPV) is an important cause of disease in domestic dogs. Sporadic cases and outbreaks occur across Australia and worldwide and are associated with high morbidity and mortality. Whether transmission of CPV occurs between owned dogs and populations of wild dogs, including [...] Read more.
Canine parvovirus (CPV) is an important cause of disease in domestic dogs. Sporadic cases and outbreaks occur across Australia and worldwide and are associated with high morbidity and mortality. Whether transmission of CPV occurs between owned dogs and populations of wild dogs, including Canis familiaris, Canis lupus dingo and hybrids, is not known. To investigate the role of wild dogs in CPV epidemiology in Australia, PCR was used to detect CPV DNA in tissue from wild dogs culled in the peri-urban regions of two Australian states, between August 2012 and May 2015. CPV DNA was detected in 4.7% (8/170). There was a strong geospatial association between wild-dog CPV infections and domestic-dog CPV cases reported to a national disease surveillance system between 2009 and 2015. Postcodes in which wild dogs tested positive for CPV were 8.63 times more likely to also have domestic-dog cases reported than postcodes in which wild dogs tested negative (p = 0.0332). Phylogenetic analysis of CPV VP2 sequences from wild dogs showed they were all CPV-2a variants characterized by a novel amino acid mutation (21-Ala) recently identified in CPV isolates from owned dogs in Australia with parvoviral enteritis. Wild-dog CPV VP2 sequences were compared to those from owned domestic dogs in Australia. For one domestic-dog case located approximately 10 km from a wild-dog capture location, and reported 3.5 years after the nearest wild dog was sampled, the virus was demonstrated to have a closely related common ancestor. This study provides phylogenetic and geospatial evidence of CPV transmission between wild and domestic dogs in Australia. Full article
(This article belongs to the Special Issue Advances in Parvovirus Research 2020)
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Open AccessReview
The Interplay between Adeno-Associated Virus and Its Helper Viruses
Viruses 2020, 12(6), 662; https://doi.org/10.3390/v12060662 - 19 Jun 2020
Viewed by 487
Abstract
The adeno-associated virus (AAV) is a small, nonpathogenic parvovirus, which depends on helper factors to replicate. Those helper factors can be provided by coinfecting helper viruses such as adenoviruses, herpesviruses, or papillomaviruses. We review the basic biology of AAV and its most-studied helper [...] Read more.
The adeno-associated virus (AAV) is a small, nonpathogenic parvovirus, which depends on helper factors to replicate. Those helper factors can be provided by coinfecting helper viruses such as adenoviruses, herpesviruses, or papillomaviruses. We review the basic biology of AAV and its most-studied helper viruses, adenovirus type 5 (AdV5) and herpes simplex virus type 1 (HSV-1). We further outline the direct and indirect interactions of AAV with those and additional helper viruses. Full article
(This article belongs to the Special Issue Viral Coinfection)
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